ATP-binding cassette (ABC) transporter vesicles are easy-to-use, efficient reagents for early assessment of a drug candidate’s substrate and drug interaction potential. Prepared from Sf9 cells which have been engineered to over-express specific ABC transporters, these “inside-out” vesicles provide high levels of transporter activity with low background, giving you a clear signal if your compound is a substrate or inhibitor of a specific efflux transporter. ABC Transporter Vesicles, which have an inside-out structure, are prepared from ABC transporter membranes for use in vesicular transport assays. While ABC transporters typically mediate the efflux of substrates from cells, transporters expressed on these inside-out vesicles import substrates into the vesicles. It is therefore possible to quantitatively evaluate transport activity for your compound by determining the amount incorporated into the vesicles.